1. Field of the Invention
The present invention is based on a method for pressing signals of a tire pressure monitoring system.
2. Description of the Prior Art
A method of this kind is known from WO 93/16891, and operates with a "wheel electronics package," mounted on the respective wheel, which contains a pressure sensor, a circuit for processing the pressure measurement signal, a transmitter with transmission antenna, and a battery, in combination with reception antennas, associated with the wheels, which are connected to a common "control device" in the body which contains a common receiver for the reception antennas, an analysis circuit, and a display unit. In order for the control device to be able to assign the received signals unequivocally to the respective wheels of the vehicle, each wheel electronics package equips the signals that it sends out with an individual identifier (identification signal). For this purpose, the wheel electronics packages generate signals divided into four segments, comprising a preamble (synchronization portion of the signal); the identification signal (identifier), in particular in the form of an identification number; a measurement signal which provides information concerning the measured tire pressure; and a postamble constituting the end of the signal (CRC signal). In order to be able to determine, on the basis of the identification signal, the wheel from which a signal is coming, according to WO 93/16891 an initialization is first performed during which the respective identification signal associated with the respective wheel position is stored in the control device. In order to perform this initialization, the tire pressure monitoring system must be switched into a "pairing mode," and then each individual transmitter must be activated in sequence. The system is then switched back into its measurement mode until the transmitter positions change as a result of a wheel change. In other words, a suitably trained person must perform the initialization at each wheel change. Wheel changes in any repair shop or at home are therefore, in some circumstances, impossible or possible only at the risk of safety. Correct functioning of the tire pressure monitoring system cannot be guaranteed due to possible operating errors.
In WO 93/08036 the problem is circumvented by recording the data from the pressure sensors and the transmission electronics connected thereto not with the aid of the central control device provided in the vehicle, but rather with the aid of a remote control element which has an LCD display device allowing the tire pressure to be read off. To determine the tire pressure, the desired information must be ascertained at each individual wheel with the aid of the remote control element. The known method does offer the advantage of unequivocal allocation of the measured values, but does not allow monitoring of the tire pressure while driving.